Answer to Question 1
The factors will include: the size of the debt at that time, how long it will take to pay off the debt, and the interest rate on the existing debt.
Answer to Question 2
The debt ratio is simply the ratio of the stock of debt to GDP. So, the debt ratio will rise whenever the increase in debt is greater than the increase in GDP. Even if the primary deficit is zero, the debt ratio will increase if the interest payments on the existing debt are such that they more than offset the fact that the economy is growing. So, a comparison of the real interest rate and growth rate of GDP will be important. Also, the debt ratio will rise if the primary deficit exists (or increases).
Ancient Warming Shrunk Horses to Housecat Size
Factors Affecting the Environmental Lapse Rate (ELR): Heating or Cooling of the Lower Atmosphere
Factors in Food Security
Factors That Affect BP
Formation of a DNA loop allows factors that bind to an enhancer or silencer
Relative size ranges and fluorescent dye labeling colors of 16 STR